Carbonyl CompoundsVladimíra Kvasnicová

Carbonyl functional group: C=O • carbonyl- = oxo- group• polar, planar, 2 nonbonded pairs of electrons (:O:)• it is found in aldehydes and ketones• ALDEHYDES: terminal carbon; -CHO -al• in addition to a parent chain: -carbaldehyde• prefix: formyl- (1,2,3-propane tricarbaldehyde)

• KETONES: middle carbon; -CO- - one• prefix: oxo- or keto-

Carbonyl compounds• names: systematic or common (trivial)• aldehydes: substitution principle or name

derived from common name of a corresponding acid

• ketones: substitution principle / radical function principle or common names

• properties: formation of H-bonds with water solubility of low

MW carbonyl compounds in water (C1-C4) sharp and irritant odour ( MW) – toxic comp.,

alergy;or pleasant smell ( MW)

Carbonyl compounds• important aldehydes:

methanal = formaldehyde ethanal = acetaldehyde 2,3-dihydroxypropanal = glyceraldehyde benzaldehyde (bitter almond odour, little toxic)

• important ketones: propanone = dimethyl ketone = acetone 1,3-dihydroxypropanone = dihydroxyacetone

ketones are more narcotic than aldehydes

Carbonyl compoundsAromatic ketones• with phenyl group: phenones (-

ophenone)• with naphtyl group: naphtones (-

naphtone)• root of acyl name (= rest of a carboxylic acid)

+ the suffix acetophenone = methyl phenyl ketone benzophenone = diphenyl ketone 2-acetonaphtone = methyl 2-naphtyl ketone

Carbonyl compounds - REACTIONS1. oxidation

• prim. alcohol aldehyde carboxylic acid• sec. alcohol ketone no more oxidized

Tollens´ reagent: Ag(NH3)2+ AgBenedict´s or Fehling´s solution: Cu2+(l) Cu2O (s)

2. reduction• aldehyde primary alcohol• ketone secondary alcohol

Carbonyl compounds - REACTIONS3. addition reactions

a) addition of waterhydrate is formed (it exists only in aqueous solution)e.g. formalin

b) addition of alcoholshemiacetal or hemiketal is formed (see saccharides)= unstable compounds; but cyclic products are stableIf 2nd alcohol reacts acetals or ketals

(e.g. disaccharides)reversible reaction: hydrolysis

c) addition of nitrogen compoundsimine is formed (it is important in biochemistry)

Carbonyl compounds - REACTIONS

4. reactions of alpha carbon atom (= 2nd C)

• the carbon is somewhat acidica) keto-enol tautomers (constitutional isomers)

aldehydes and ketones exist in an equilibrium mixture of the keto and enol forms

b) aldol condensation= reaction between two molecules of carbonyl compounds -hydroxyaldehyde („aldol“) is formed

EXERCISE

• cyclohexanol• cyclohexane

carbaldehyde• cyclohexanone• dicyclohexyl ether• diphenyl ether• phenol -naphtol• benzyl alcohol

• phenyl propyl ether• ethyl methyl ketone• propanal• methyl phenyl ether• methyl phenyl ketone• 2-

methylcyclopentanone• 1-hydroxybutanone• benzaldehyde